Documents show BP chose a less-expensive, less-reliable method for completing well in Gulf oil spill

Oil company BP used a cheaper, quicker but potentially less dependable method to complete the drilling of the Deepwater Horizon well, according to several experts and documents obtained by the Orlando Sentinel.

"There are clear alternatives to the methods BP used that most engineers in the drilling business would consider much more reliable and safer," said F.E. Beck, a petroleum-engineering professor at Texas A&M University who testified recently before a U.S. Senate committee investigating BP's blown-out well in the Gulf of Mexico.

He and other petroleum and drilling engineers who reviewed a log of the Deepwater Horizon's activities obtained by the Sentinel described BP's choice of well design as one in which the final phase called for a 13,293-foot-long length of permanent pipe, called "casing," to be locked in place with a single injection of cement that can often turn out to be problematic.

A different approach more commonly used in the hazardous geology of the Gulf involves installing a section of what the industry calls a "liner," then locking both the liner and a length of casing in place with one or, often, two cement jobs that are less prone to failure.

The BP well "is not a design we would use," said one veteran deep-water engineer, who would comment only if not identified because of his high-profile company's prohibition on speaking publicly about the April 20 explosion aboard the Deepwater Horizon or the oil spill that started when the drilling rig sank two days later.

He estimated that the liner design, used nearly all the time by his company, is more reliable and safer than a casing design by a factor of "tenfold."

But that engineer and several others said that, had BP used a liner and casing, it would have taken nearly a week longer for the company to finish the well — with rig costs running at $533,000 a day and additional personnel and equipment costs that might have run the tab up to $1 million daily.

BP PLC spokesman Toby Odone in Houston said the London-based company chooses between the casing and liner methods on a "well-by-well basis" and that the casing-only method is "not uncommon."

Investigators and Congress have already homed in on a series of suspected instances of recklessness or poor maintenance aboard the Deepwater Horizon — looking, for example, at why the well's blowout preventer failed. Those instances, taken together, may have weakened the rig's defenses and fueled the April 20 explosion on the rig, which killed 11 workers and caused the biggest offshore-drilling spill in U.S. history.

Many of the experts interviewed by the Sentinel for this report, including Beck, would not directly criticize BP's choice of well design because some site-specific factors might still not be publicly known. But those experts provided extensive details about, and insight into, the company's chosen approach for completing the well versus the alternative method that's more commonly used by drillers in the Gulf.

Several other major companies active in the Gulf of Mexico, including Shell, Chevron and Marathon, declined to comment on their well designs.

"We're confident that the incident is being thoroughly investigated and findings will be communicated across the industry to prevent such events from occurring in the future," said Shell spokeswoman Kelly op de Weegh in Houston.

Formidable

Hunting for enormously rich deposits of oil and natural gas in deepwater regions of the Gulf of Mexico entails some of the most formidable drilling in the world. And BP's ill-fated Macondo exploratory well had more than its share of trouble and warning signs, according to the rig's activity log, or "well ticket."

Drilling began last year on Oct. 7, in water 4,992 feet deep and nearly 50 miles southeast of the tip of Louisiana's Mississippi River delta.

The first 4,023 feet of drilling was done by the rig Marianas, owned by the Switzerland-based Transocean Ltd. But a month later, that rig was damaged by Hurricane Ida and towed to a shipyard. Transocean's Deepwater Horizon, fresh from drilling a record-deep well elsewhere in the Gulf, arrived to take over by early February.

The rig, weighing about as much as the 900-foot-long Titanic and considered one of the most capable drilling vessels in the world, almost immediately encountered some of the problems for which the Gulf is known.

Beneath the Gulf's seafloor is a mush of sand, shale and salt in formations that are geologically young, unsettled and fragile. Coupled with that are layers of sand that hold crude oil and natural gas under high pressure.

For rigs such as Deepwater Horizon, drilling a Gulf well means working between a dangerous rock and a risky hard place.

While boring into the Earth's crust, a rig pumps a chemical slurry called "mud" down the center of the drill pipe. The mud exits through the drill bit in a blast that washes cuttings out of the freshly cut hole and back up to the rig.